An absorbent article includes, among other things, a bottom liquid-impermeable backing sheet, an absorbent sheet or layer on top of the backing sheet, and an uppermost liquid-permeable surface sheet which is intended to lie proximal to the wearer in use. The sheets are delimited by two transverse edges and two longitudinal edges. When the absorbent article is a diaper or an incontinence protector, the transverse edges will form waist edges and the longitudinal edges will form leg edges. The diaper will then include a front and a rear end-part and an intermediate crotch part which, in use, will lie between the wearer""s thighs. So that the article will fit the wearer, it is provided with side-flaps that extend laterally beyond both sides of the absorbent body and at least within that part, which is intended to form the crotch part when using, longitudinal elastic devices along the free side-edges of the side-flaps. The elastic devices serve as leg elastic when the article is worn and are intended to abut the wearer""s thighs and shape the article. The flexible side-flaps form sealing edges and are intended to prevent liquid and faeces from leaking out at the edges, in other words they form barriers.
In order to further escape the risk of leakage at the side edges, some absorbent articles also include additional, inner liquid barriers or cuffs, also called standing barriers, fastened in the proximity of the longitudinal edges of the article. The liquid barriers are intended to prevent liquid leaking out at the edges of the absorbent article and also to prevent leakage of any solid matter, such as faeces. This further liquid barrier is positioned inwardly of the leg elastic, i.e. the outer liquid barrier, and is normally made of an essentially liquid-impermeable material, e.g. nonwoven material, although it may alternatively be made of a liquid-permeable material. The liquid barrier is comprised of a web of material whose one longitudinal edge is fastened to the absorbent article and the other edge, its free edge, is intended to lie against the wearer in use. The free edge is gathered or puckered elastically with the aid of an elastic thread that is enfolded in the edge of the web. Examples of diapers that include liquid barriers are described in WO-A1-9207533, SE-T3-0 264 238 and GB-A-2 188 532, for instance. When the absorbent article has liquid barriers positioned inwardly of the flexible side-flaps, the surface material or top sheet material that is located between the two inner liquid barriers, i.e. located in the liquid acquisition region, will be permeable to liquid, while the surface material or top sheet material outside said liquid barriers will be essentially impermeable to liquid.
In the case, e.g., of diapers that include inner liquid barriers or cuffs, the barriers are positioned so as to lie against the wearer""s thighs and buttocks and therewith prevent leakage. A given volume of urine is discharged into the diaper each time the wearer urinates. Since it takes a little time for the urine to penetrate through the surface sheet and be absorbed in the absorbent sheet, or layer, some of the urine will xe2x80x9cfloatxe2x80x9d on the surface sheet of the article. It is this volume of urine that the barrier shall prevent from leaking out at the edges of the absorbent article.
One edge of the liquid barrier is fastened to the absorbent article. One way of fastening the barrier is to weld said edge firmly to the surface sheet. The ends of the barrier placed at the transverse edges of the article are often folded down flat against the surface sheet and either welded or glued thereto. Any liquid that comes onto this surface, which is substantially liquid-impermeable, will not be absorbed by the article, but will run out at the edges thereof. This can be the case, for instance, when boys lie on their backs with their penises pointing obliquely to one side/or upwards towards the waist part of the diaper. When they urinate, the urine will land at the front part of the diaper in the vicinity of its transverse edge or longitudinal edge, and possibly on the downwardly folded part of the liquid barrier. The diaper will then leak, normally in the region of the wearer""s groins or waist. This can also occur in respect of boys that are not lying on their backs, but with whom the penis has been xe2x80x9cwrongly positionedxe2x80x9d when putting on the diaper, such as to point upwards. It has also been found that liquid will leak likewise in the barrier itself. Liquid leaks out at the elastically gathered edge that lies in abutment with the wearer. Because the barrier edge that lies in abutment with the wearer is gathered, or puckered, it will include narrow through-passing pores or channels in the contact surface between the barrier and the wearer""s skin. Liquid is able to penetrate through these pores or channels, when the liquid pressure is excessively high. Folds and pleats can also form in the barrier edge, therewith resulting in liquid escaping at said edge. Surface material that is substantially impermeable to liquid is normally present outwardly of the barrier and any liquid that leaks out will xe2x80x9cfloatxe2x80x9d on this essentially liquid-impermeable material. In this regard, there is a serious risk of liquid leaking out through the leg elastic, the outer barrier.
The object of the invention is to solve these problems.
The present invention relates to an absorbent article that will reduce leakage primarily at the front end-part of the diaper. According to invention, this is achieved by rendering permeable to liquid at least one part of the essentially liquid impermeable regions of and/or on the surface sheet at a front and/or rear end thereof, so that liquid will be able to penetrate quickly into the underlying absorbent sheet or layer.
The use of perforated material is known in the art, for instance from EP 409 535. This material is used, e.g., as the so-called surface sheet or top sheet in absorbent products. According to this EP-specification, the function of the surface sheet material is to form a bulky nonwoven layer that is soft and allows water and gas to pass readily therethrough and effectively absorb moisture. The perforations are formed in a special way such as to obtain a cylindrical shape, where the vertical extension (the height) of said perforations is at least two times the thickness of the surface sheet material. The diameter of the holes or perforations is also said to have different dimensions. In distinction to this document, the present invention relates to the perforation of the material at the ends of the liquid barriers and in the forward and rearward ends of the side-flaps in said surface sheet. In conventional absorbent articles, these materials are usually essentially liquid-impermeable, but are made permeable to liquid in the present invention so that liquid will pass easily and quickly therethrough. This is preferably achieved by perforating the materials, although the invention also relates to other methods.
There is described in EP 745 367 a diaper that includes plastic film liquid barriers. These barriers shall be liquid impermeable and able to breathe at the same time. This is achieved with a barrier that consists of two mutually spaced sheets of plastic film. A plurality of tubular passageways extend from the outer surface of the barrier to its interior. The passageways are configured so that whereas liquid can readily enter into the passageways it is unable to exit therefrom. They are also preferably placed on respective sheets so as not to be linear with one another. Thus, this barrier will not be permeable to liquid even though liquid can enter the actual barrier. The xe2x80x9cbreathingxe2x80x9d function achieved with the barrier passageways is utilised in the upstanding part of the barrier. According to the present invention, parts of those regions of the surface sheet that are liquid-impermeable or covered with a liquid-permeable material in the forward and/or the rearward end-part thereof are made liquid-permeable so that liquid can be sucked down into the underlying absorbent sheet or layer.
The present invention thus relates to an absorbent article, such as a diaper, an incontinence protector or like article, that includes a front and a rear end-part, an intermediate crotch part which is intended to be placed between the wearer""s thighs in use, longitudinal and transversal edges, a bottom liquid-impermeable backing sheet, an absorbent sheet, longitudinally extending liquid barriers fastened along or on the longitudinal edges of the article and including a free, stretchable edge which is gathered or puckered at least at its centre part, side-flaps which extend laterally outside the liquid barriers, and longitudinally extending elastic elements along the free side-edges of said side-flaps at least in said crotch part, said elastic elements functioning as leg elastic when the article is worn, a first essentially liquid-permeable surface sheet or top sheet between said liquid barriers, and a second essentially liquid-impermeable surface sheet or top sheet outwardly of said liquid barriers, wherewith the ends of the liquid barriers are folded down flat at the front and/or the rear end-part and fastened against the first and/or the second surface sheet, and wherewith the regions of the surface sheets in the front and/or rear end-part consist of an essentially liquid-impermeable material or are covered by an essentially liquid-impermeable material, wherewith at least a part of said regions has been made permeable to liquid, preferably by perforating down to the absorbent sheet or layer that extends beneath at least portions of said part; and in that the part of said regions that has been made permeable to liquid is located within at least parts of the downwardly folded ends of the liquid barriers and/or the second surface sheet.